Cystic fibrosis (CF) is a hereditary chronic disease affecting human patients that causes the buildup of thick, sticky mucous in the lungs and other parts of the body. If left untreated, the mucous can clog air ways, and lead to complications such as tissue inflammation or infection, or other symptoms such as coughing, phlegm, and compromised cardio-respiratory performance.
One technique to manage CF is chest physiotherapy (CPT) which involves the manipulation of the patient's thorax to dislodge mucous buildup in the airways and encourage expectoration of the mucous. CPT may have to be performed in several sessions in a day, with each session lasting from between 10 to 45 minutes. CPT can be performed manually by therapists who use their hands to repeatedly percuss (clap, thump or press against) the patient's thorax. However, manually performed CPT can be physically and time demanding and should be performed by a properly trained therapist. Alternatively, CPT can be performed using handheld or wearable mechanical devices. Wearable devices have the advantage over handheld devices of relieving the therapist or patient from having to manipulate the device during the treatment session.
Some wearable devices administer pulsating pneumatic pressure to the patient. U.S. Pat. No. 4,838,263 to Warwick et al, describes a vest bladder containing an air chamber and a pressurizing means to alternately pressurize and depressurize the air chamber to produce a pulsating compression on the patient's thorax. U.S. Pat. No. 6,036,662 to Van Brunt et al. describes a vest containing an air bladder that coverts pulses of air into compressions to the patient's thorax. US Pat. Application No. 2005/0234372 to Hansen et al. describes a vest with an internal air chamber for receiving repeated pulses of air, which translate through the vest as pressure pulses against the patient's thorax. However, these devices rely on intimate contact between the vest and the patient's thorax and tend act over a relatively large area of the patient's thorax, with the result that they may constrict the patient's normal breathing motions.
Some wearable devices sonically transmit pressure waves to the patient generated by an acoustic transducer. U.S. Pat. No. 6,193,677 to Cady describes a vest incorporating a speaker to deliver low frequency pulsed audio signals to the patient. U.S. Pat. No. 6,193,677 to Plante describes a vest with a plurality of pockets or a harness-type arrangement to support an acoustic transducer to propagate acoustic waves via an acoustic coupling chamber to the patient. US Pat. Application No. 2008/0108914 to Brouqueyre et al. describes a vest with a vibration unit to transmit low frequency acoustic waves through a form-fitting material like a gel or fluid contained in the inner surface of the vest. However, transmission of pressure waves through a compressible medium may not be as efficacious as direct mechanical manipulation of the patient's thorax.
Some wearable devices administer mechanical impacts or vibrations to the patient. U.S. Pat. No. 3,310,050 to Goldfarb describes a vest-like garment or harness-type arrangement with a plurality of pockets to support a plurality of electro-mechanical vibrators to produce pulsating impacts that are communicated to the patient either by direct contact with the patient or indirectly through coupling constituted by the vest material and webbing belts. U.S. Pat. No. 5,235,967 to Arbisi et al. describes a vest-like garment with an internalized frame continuous throughout the garment, containing a plurality of movable electrically conductive elements that are actuated by a pulsed magnetic field produced by drive coils that are energized by a drive circuit. U.S. Pat. No. 5,261,394 to Mulligan et al. describes a percussive aid comprising arms that are reciprocally driven between a cocked position and a contact position by a drive mechanism, within a frame curved to fit the patient and adapted to be worn like a backpack, secured to the patient's thorax by shoulder and waist straps. US Pat. Appl. No. 2006/0089575 to DeVlieger describes a rigid element with pads clamped to the body, which transmit vibrations from an attached vibrator. The effectiveness of such devices depends on the ability to maintain contact at the interface between the device and the patient.
Accordingly, there remains a need for a wearable thorax percussion device that provides for effective, comfortable, convenient and consistent treatment of the patient.